Wilber j



(No Model.)

W. J. CUNNINGHAM.

VALVE GEAR.

No. 451,812. Patented May 5,1891.

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UNITED STATES IVILBER J. CUNNINGHAM, OF RAPID OITY, SOUTH DAKOTA, ASSIGNOR OF ONE-HALF TO LA FAYETTE L. DAVIS, OF SAME PLACE.

VALVE-G EAR.

SPECIFICATION forming part of Letters Patent No. 451,812, dated May 5, 1891.

Application filed September 4, 1890. Serial No. 363,918. (No model.)

To aZZ whom it may concern.-

Be it known that I, WILBER J. CUNNING- HAM, of Rapid City, in the county of Pennington and State of South Dakota, have invented a new and Improved Valve-Gear, of which the following isa full, clear, and exact description.

The object of the invention is to provide a new and improved valve-gear especially designed for steam-engines, and which is simple and durable in construction, very effective in operation, and insures a quick opening and clos ng of the ports at the proper time.

The invention consists of a circular cam arranged on the main driving -shaft, and valve-stems mounted to turn and adapted to be turned by the said cam, the valve-stems actuating the slide-valves.

The invention also consists of certain parts and details and combinations of the same, as will be fully described hereinafter, and then pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar letters of reference indicate corresponding parts in all the figures.

Figure 1 is aplan view of the improvement.

Fig. 2 is a sectional side elevation of the same on line a: 00 of Fig. 1, and Fig. 3 is a tranverse section of the improvement on the line y y of Fig. 2.

The steam-engine on which the valve-gear is applied is provided with the usual cylinder A, in which operates a piston connected in the usual manner with the main driving-shaft B, on which is secured a circular cam O, the rim of which is spirally arranged, as is plainly shown in Fig. 1. The circular cam O is engaged at opposite places by sets of frictionrollers D and D, held on arms E and E, respectively mounted to turn loosely on crankarms F and G, respectively secured on valvestems H and I, respectively mounted to turn in suitable hearings on the frame of the engine. The ends of the valve-stems H and I pass through suitable stuffing-boxes into the steam-chest J, connected with a steam-supply and also by suitable ports with the cylinder A. On the ends of the valve-stems H and I, projecting into the steam-chest J, are secured arms K and L, respectively connected by links N and 0, respectively, with slide-valves P and Q, adapted to open and close the ports leading to the ends of the cylinder A, and also control the-exhaust. The operation is as follows: When steal is admitted to the steam-chest J, it passes through one of the open ports into the respective end of the cylinder A, so that steam exerts its pressure on the piston and the main driving-shaft B is revolved. One of the valves is open while the other is closed Now when the main driving-shaft B is turned the spiral cam G acts quickly on the sets of friction-rollers D and D, so that the crankarms F and G are swung, thereby turning the valve-stems II and I, so that the positions of the valves are changed, that the one which was previously closed is now open and the one which was open is closed. The friction-rollers D and D are mounted in the arms E E for the purpose of permitting the latter to turn on their bearings to reduce friction to a minimum. The sets of frictionrollers D and D are preferably arranged about two-thirds of the periphery of the spiral cam O apart, so that the opening and closing of the valves P and Q take place at twothirds stroke.

Having thus fully described my invention, I claim as new and desire to secure by Letters Patent 1. In a valve-gear, the combination, wit-l1 a spiral cam secured on the main driving-shaft, of valve-stems adapted to be turned from the said cam and adapted to actuate slide-valves, substantially as shown and described.

2. In a valve-gear, the combination, witha spiral cam secured on the main driving-shaft, of valve-stems mounted to turn and actuated from the said spiral cam, and slide-valves actuated by the rocking of the said valvestems, substantially as shown and described.

3. In a valve-gear, the combination, with a spiral cam secured on the main driving-shaft, of sets of friction-rollers engaging the spiral rim of the said spiral cam, crank-arms supporting the said friction-rollers, and valvestems mounted to turn and carrying the said crank-arms, and also adapted to actuate the slide-valves, substantially as shown and described.

4. In a valve-gear, the combination, with a and slide-valves connected with the said secsplrai cam secured on the main driving-shaft, 0nd set of crank-arms, substantially as shown 10 of sets of friction-rollers adapted to engage and described.

the spiral rim of the said cam, arms carrying T. T 5 the said friction-rollers, crank-arms on which ELDER (JUL NIB GHAM' the said arms are mounted to turn, valve- XVitnesses:

stems carrying the said crank-arms, a second FRED M. BROWN,

set of crank-arms held on the said valve-stems, G. THOMSON. 

